Changed structure to make_enum tools, added some options

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branch : pure-cffi
iosource requires setup.

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branch : pure-cffi
fix previous bookmark mistake.

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branch : pure-cffi
fix read and seek test

and we don't need yet the write function.

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branch : pure-cffi
fix callbacks for IOSource/AVIOContext

the problem was an uncareful managing of the callback lifetime.
Of course the callback( object)s must have an explicit lifetime
greater or equal of the avio wrapper.

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branch : pure-cffi
fix the demuxer open. Full coverage. Yay!

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branch : pure-cffi
explicitely guard against multiple setup() calls

doing all the work all the time should be harmless,
but is still wasteful.

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branch : pure-cffi
docstrings.

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branch : pure-cffi
explain why we need an explicit double pointer here.

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branch : pure-cffi
add notes about the samples.

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branch : pure-cffi
drop explicit setup counter (useless)

more ffmpeg wrapping.

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branch : pure-cffi
start to implement the stream (info gathering) in the demuxer.

--HG--
branch : pure-cffi
Merge ../pyrana